Field of the Invention
The present invention relates to a solid-state image sensor, a driving method thereof, and a camera.
Description of the Related Art
A solid-state image sensor includes, for example, a plurality of pixels arrayed in a matrix, a driving unit, a readout unit, a transferring unit, and an output unit. The driving unit is a vertical scanning circuit including, for example, a shift register and drives, based on a synchronizing signal, the plurality of pixels while scanning them for each row. The readout unit reads out pixel signals from the driven pixels. The transferring unit is a horizontal scanning circuit including, for example, a shift register and transfers, based on the synchronizing signal, the read out pixel signals while scanning them for each column.
If, for example, shooting is not started over a predetermined period of time, power consumption of the solid-state image sensor can be reduced by setting an operating mode of some units to a sleep state. This can be done by, for example, stopping power supply to a control target unit.
Japanese Patent Laid-Open No. 2006-081048 describes setting an order of changing the states of a plurality of units which constitute a solid-state image sensor in order to prevent an unexpected forward bias current from being caused by a PN junction in the solid-state image sensor. However, Japanese Patent Laid-Open No. 2006-081048 does not disclose a way of determining a timing to change the state of each unit.